Safety lights and other devices foreseen for use in emergency situations involving the risk of drowning or the like often include sensors for detecting the presence of water. These sensors provide an indication, for example, that they are submersed in water which can be used by the device to enter a different state, for example triggering an alarm or illuminating a light or the like. Some prior art sensors suffer the drawback that they are easily triggered by splashing or the like which, although an indication that water is present, does not necessarily indicate that the sensor has been submersed. Other prior art sensors, although resistant against the intermittent effects of splashing, suffer adversely from corrosion and may give rise to false readings if exposed repeatedly to a corrosive environment.